Chiptune music is the art of using classic computing hardware to make original tunes. Usually, there's software involved, such as DMS Drummer, and the result is emitted from the device's inbuilt speakers.

The sound comes from a magnetic head moved by stepper motor. To make a specific sound, head must be moved with appropriate frequency… To move the head you need to activate the drive by pulling the DRVSB0 or 1 (depends on the cable you have and the connector – notice the crossover on the FDD ribbon cable) pin low and then falling edge on STEP pin makes the head move one step in direction dependent on DIR pin state. An ATMega microcontroller is generating those frequencies and it makes the drives play music.

Listen to Amiga floppy drive playing a simple music, however, not with the step motor which moves the head, but with the motor which spins the disk. This means that disk must be inserted to hear music. And there is no fear that floppy will break like with the step motor music!

I've yet to find any such musical demonstrations that feature an Apple II floppy disk. Do you have some? Let me know!